In recent decades, the semiconductor community has made attempts to improve integrated circuit (IC) processing by replacing lithography steps with alternatives that translate to lower cost, reduced processing time, and smaller feature sizes. Many of these alternatives fall under the blanket category of “selective deposition.” In general, selective deposition refers to a process for which the net deposition rate is higher on the target substrate material relative to other substrate materials, such that the film thickness is achieved on the target substrate material with negligible deposition on the other substrate materials (where “negligible” is defined by process constraints).
Selective deposition is believed to be an effective technique to significantly reduce the cost of the patterning process in semiconductor device fabrication. Selective deposition helps reduce the complexity of process flow resulting in less process steps and higher throughput.
One general strategy to achieve selective deposition employs the use of blocking layers. Ideally, this strategy involves (1) formation of a blocking layer on substrate materials on which deposition is to be avoided with negligible impact to the target substrate material, (2) deposition on the target substrate material (where deposition on other substrate materials is “blocked” by the blocking layer), and (3) removal of the blocking layer without net adverse effects to the deposited film.
One manner of selective deposition uses self-assembled monolayers (SAMs) to enhance the process or deposition selectivity. One of the key elements of a SAM selective deposition process is the quality of the SAM. For example, a layer of defect free and well packed SAM is important for achieving high quality selective deposition. A SAM defect is any form of nanometer size particles or contaminates generated during SAM deposition process. These particles or contaminants can eventually translate into a failed circuit and cause device yield loss. In addition, the packing quality of SAM molecules determines the blocking efficiency which is related to the deposition selectivity. Accordingly the application of selective deposition is largely dependent on the quality of the SAM layer.
Therefore, there is a need in the art for apparatus and methods to achieve high quality defect free SAM on dielectric or metal surfaces.